A lot has happened this week on the North Korean front, and rather than discuss each discrete issue in one mega post I’ll stretch them, when able, over a number of posts.
One of the things, I’ll confess, that threw me about the July 28 Hwasong-14 ICBM test, after seeing very early reports of the data (ie well before North Korea released the obligatory pictures and videos), was that it wasn’t really a new missile.
I expected that a true, as opposed to limited ICBM or extended range IRBM, North Korean ICBM with the capability to hit the US mainland wouldn’t use one first stage booster engine. I initially strongly suspected, and articulated that suspicion, that the July 28 ICBM test used a cluster of Hwasong-12 and Hwasong-14 July 4 engines.
I expected to see a cluster because I didn’t really think that North Korea could use just the one Pektusan or March 18 Revolution engine for a first stage ICBM, because the nuclear warhead would be too heavy. That is, the throw-weight of the missile wouldn’t be suited for ICBM range missions.
But then, alas, the first stage booster engine was the Hwasong-12 and Hwasong 14 July 4 booster engine.
The first thing I want to talk about is some aspects, those directly related to the above comments, of the Hwasong-14 ICBM that is dividing the technical arms control and strategic studies community at the moment.
This week saw a report in The Washington Post, based on US (DIA) and Japanese intelligence, stating that North Korea has a nuclear warhead of sufficient compactness to fit atop the Hwasong-14 such that the missile can strike mainland US targets with a nuclear payload.
That was a real attention grabber, that was.
The way I saw things previously was that the Hwasong-14 first stage engine was very similar to the Soviet RD-250 engine, and had thrust performance parameters much like the booster engines (clustered) used on the Chinese Chang Zheng 2C SLV and/or DF-5 ICBM, which used a cluster of 4 engines for the first stage. The CZ 2C could loft a 2,500kg payload into low earth orbit.
Now, the RD-250 formed the basis of the first stage of the Soviet SS-9 ICBM but it was clustered, ie three two camber engines, and that configuration was known as the RD-251. The DF-5/Long March 2 used a cluster of. Both missiles had large throw weights, the SS-9 3950 to 5825kg.
I didn’t really think that the North Koreans had a compact warhead able to be delivered to intercontinental ranges by a missile whose booster stage was just the one Pektusan or March 18 Revolution engine.
Postol, Schiller and Schumcker adopt a similar position in a most impressive technical study published by the Bulletin of the Atomic Scientists. This paper is a gold mine, I’ll keep referring to it, and will only scratch the surface here.
One thing to note is that the conclusion of the paper is framed within Schiller’s “bluff hypothesis,” which I will discuss in another post.
Postol, Schiller and Schumcker and conclude here that the Hwasong-14 is, to quote Mao, a paper tiger.
The Hwasong-14 is a paper tiger because it cannot deliver a nuclear warhead of weight and dimensions matching North Korea’s physics package capabilities, as well as penetration aids such as decoys, to the contiguous United States. Penetration aids are needed to complicate the task of Ballistic Missile Defense.
The thing is we don’t know, based on publicly available information, how compact North Korea’s nuclear warhead is. North Korea has conducted 5 nuclear tests, as has India, and Pakistan 6. The likely yields of the respective testing programmes, shorn of inflated Indian and Pakistani official data, are not too far off from each other.
Pakistan is reputed to have a 400kg low yield nuclear warhead for the highly controversial Nasr short range ballistic missile. That’s at the low end of Postol, Schiller and Schumcker’s weight estimates. However, the Nasr missile is meant to deliver a low yield battlefield tactical nuclear warhead. A North Korean ICBM warhead, of higher yield, must be protected from the rigours of atmospheric reentry.
So, you’d think that the Postol, Schiller, Schumcker lower bound of 400kg is about right. They argue that lower bound is unlikely to be the actual weight of the nuclear payload, for reasons stated above.
India’s Agni IV long range missile reputedly has a throw weight of 800kg, and can deliver a 30 to 45KT warhead to targets in China (3500 to 4000km).
Is that the best the Indians can do for a fission bomb (30 to 45KT is boosted fission recall) to be delivered to relatively long ranges with data from only 5 nuclear tests? Can the North Koreans do better than the Indians? If so, upon what basis?
If you use 800kg and plug that into the Postol, Schiller, Schmucker graph based on their model of the July 28 Hwasong-14 then you don’t get an ICBM able to target the lower 48 US states. Even if you use John Schilling’s relatively more optimistic (from Pyongyang’s perspective) graph based on his model of the Hwasong-14 July 28 missile then you also don’t have an ICBM able to target the lower 48 US states.
I myself am of the view that North Korea wants the ability to deliver a hydrogen bomb to US mainland targets, and the Hwasong-14 is not the missile for this.
See also the remarks on this from Siegfried Hecker and David Wright, more on those later as well. The latter wrote the paper, with Timur Kadyshev, on North Korean missiles during the early years sort of our version of “On the Electrodynamics of Moving Bodies.”
One good thing about the Postol et al paper is that it makes the same point about the RD-250 and the Pektusan engine that I had made previously, that is its Ukrainian, not Russian, origins.
As an aside. The SS-9 used the most powerful Soviet nuclear warhead deployed, the 8K67, which had a yield of 10MT. In the MIRVed version the SS-9 had 3 2MT warheads. The interesting thing about that is that these high yield warheads placed US Minuteman ICBM Launch Control Centres under threat of attack, the first instance of “Minuteman vulnerability.”
The solution to this problem was the redundant internetting of Minuteman LCCs.
So, what do the Hwasong-14 and the Internet have in common? They both find their origins in the Soviet SS-9 ICBM.